Butler took over with Belles sitting third bottom of FAWNL Division One Midlands and really struggling to win games.
Sunday’s victory over Wem Town was Belles’ ninth win from 13 games this season and increased their lead at the top of the table to five points.
Jasmine Saxton’s 19th minute goal was enough to earn Doncaster another important three points in the race for the solitary automatic promotion spot.
Belles now have a five-point cushion over second-placed Long Eaton United who have a game in hand, while third-placed Lincoln City are seven points adrift but have played three games fewer.
Butler tweeted: “2 fantastic years in charge of @donnybelles, big thanks to @NickBucco1 @russgre31883829 @kayhumbo @Rcoops6 and every single player that’s given everything they can possibly give through out the seasons. The players deserve all the credit, they’re the ones doing the work!”
Belles chairman Russ Green tweeted in response: “It’s been an absolute pleasure working with these two guys [Butler and Nick Buxton], they have transformed our club both on and off the field. Their professionalism has been mirrored throughout the squad, their attention to detail and encouragement is second to none . Thank you from all at the Belles.”
Belles travel to fifth-placed Leek Town on Sunday.
Butler's side ran out 5-0 winners when the sides met in October.